This competitive revision of DA024461 is submitted under the auspices of NOT-OD-09-058: "NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications". It addresses "Gender/Sex Differences", an "Area of Scientific Priority" established by NIDA for revision applications. Heroin abuse increases the risk of HIV infection and may exacerbate HIV encephalitis (HIVE). Since a large percentage of newly infected HIV patients abuse opiates, this enhancement of disease process has serious medical and social consequences. Little is known about cellular mechanisms by which opiates accelerate and enhance the CNS neuropathology associated with HIV infection, and synergism may be multifactorial. Recent evidence from our labs and others suggests that precursors of CNS cells can be targets of HIV-mediated toxicity. Our central hypothesis, which remains unchanged in this revision, is that HIV proteins and/or HIV can target glial precursors in the CNS, and that opiates act synergistically to enhance the toxic effects of HIV. Even modest toxicity toward this population would, over time, alter the balance of glia and glial-neuronal relationships in the mature CNS. Net consequences would depend on the differential sensitivity of precursors at each stage of maturation, and might be influenced by disease duration and therapeutic regimens. Based on initial data that glial precursors and their progeny have different responses to Tat and morphine exposure, we proposed aims in the parent R01 to test if HIV viral proteins or HIV, in combination with opiates, altered production and/or survival of progenitors in vivo, thereby altering mature glial populations. In vitro studies assessed intracellular pathways activated by viral toxins and opiates. The revision application is based on studies in the literature showing gender differences in glial populations, and gender differences in response to opiates. Studies in the parent R01 were not gender balanced. We now propose to test the hypothesis that effects of HIV in combination with opiates are influenced by gender. There are two aims. Aim 1 uses in vivo models in which viral proteins are delivered opiates to show whether the survival of glial progenitors is affected by gender. Stereological assessment tests if this results in changes in glial populations. Studies in female mice will complement those proposed for male mice in the parent R01. Aim 2 tests the hypothesis that progenitors from male vs. female mice have different responses to HIV proteins and opiates in vitro, specifically examining survival, proliferation, and motility. Gender of embryos will be determined by PCR for the male sex-determining region of Y chromosome (SRY) gene. Our approach will provide novel information on whether gender affects the susceptibility of glial populations to HIV and opiates. A gender bias might predispose certain patients towards development of HIV neuropathology. PUBLIC HEALTH RELEVANCE: HIV infection and injection drug use are interlinked epidemics with devastating consequences for public health. Opioid drug abuse appears to enhance the neurodegenerative effects of HIV-1 infection. This project examines whether gender influences the interactive effects between HIV and opiate drugs of abuse on glial progenitors and mature glial populations in the brain. Identification of gender bias may lead to more effective therapeutic interventions for HIV-infected and opiate abusing individuals.